/* Copyright (C) 2004 - 2008  Versant Inc.  http://www.db4o.com

This file is part of the sharpen open source java to c# translator.

sharpen is free software; you can redistribute it and/or modify it under
the terms of version 2 of the GNU General Public License as published
by the Free Software Foundation and as clarified by db4objects' GPL 
interpretation policy, available at
http://www.db4o.com/about/company/legalpolicies/gplinterpretation/
Alternatively you can write to db4objects, Inc., 1900 S Norfolk Street,
Suite 350, San Mateo, CA 94403, USA.

sharpen is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
for more details.

You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
59 Temple Place - Suite 330, Boston, MA  02111-1307, USA. */

/* Copyright (C) 2004 - 2006 Versant Inc. http://www.db4o.com */

package sharpen.core.framework;

public class DynamicVariable<T> {

    public static <T> DynamicVariable<T> newInstance(T initialValue) {
        return new DynamicVariable<T>(initialValue);
    }

    private T _value;

    public DynamicVariable(T initialValue) {
        _value = initialValue;
    }

    public T value() {
        return _value;
    }

    public void using(T value, Runnable block) {
        T oldValue = _value;
        _value = value;
        try {
            block.run();
        } finally {
            _value = oldValue;
        }
    }

    public <TRESULT> TRESULT using(final T value, final Producer<TRESULT> producer) {
        final ByRef<TRESULT> result = new ByRef<TRESULT>();
        using(value, new Runnable() {
            public void run() {
                result.value = producer.produce();
            }
        });
        return result.value;
    }

}
